Matsya Purana — Phala-Saptamī Vow
भक्त्या तु विप्रान्सम्पूज्य चाष्टम्यां क्षीरभोजनम् दत्त्वा कुर्यात्फलयुतं यावत्स्यात्कृष्णेसप्तमी //
bhaktyā tu viprānsampūjya cāṣṭamyāṃ kṣīrabhojanam dattvā kuryātphalayutaṃ yāvatsyātkṛṣṇesaptamī //
Having reverently honored the Brahmins with devotion, on the eighth lunar day (aṣṭamī) one should give a meal of milk (or milk-based food). One should continue this observance together with fruit until the seventh lunar day (saptamī) of the dark fortnight (kṛṣṇa-pakṣa) arrives.
This verse does not address pralaya or cosmology; it focuses on vrata-dharma—devotional honoring of Brahmins and a timed dietary-gift observance across specific lunar days.
It prescribes practical grihastha/raja-dharma conduct: show reverence to learned Brahmins and perform dana (charitable giving) in a regulated way (tithi-based), emphasizing devotion, hospitality, and disciplined observance.
The significance is ritual rather than architectural: it specifies a tithi-based observance involving kṣīra-bhojana (milk-food) given on Aṣṭamī and continued with fruit until Kṛṣṇa Saptamī.